tbuckley/cabot-search huggingface dataset:
Abstract P3069: The Impact Of Lymphatic Vasculature Post-Cardiac Transplantation On Allograft Function, Fibrotic Remodeling, And Lymphatic Drainage
Authors: Sydney C Ginn, Rebecca D Levit
Journal: Circulation Research (2022)

Lymphatic drainage inherently modulates cardiac function by maintaining the immune response and tissue-fluid homeostasis. During cardiac transplantation, the lymphatic collecting vessels are severed at the time of donor heart excision and not surgically reconstructed in the recipient. We hypothesize severed cardiac lymphatics contribute to transplant rejection and reduced cardiac function by influencing myocardial edema and immune cell transit. Methods: A heterotopic abdominal heart transplant (HAHT) rodent model permitted the immunologic evaluation of transplant rejection as supported in past literature. Echocardiography confirmed allograft survival via active contraction, while histologic quantification of lymphatic vessels and fibrosis were obtained for native and transplanted rodent hearts (n=3). Lymphatic drainage was assessed via intramyocardial injection of fluorescein isothiocyanate (FITC)-dextran. Results: Electrocardiographic impulses detected during the echocardiograms revealed additional QRS complexes attributed to contractions of the transplanted hearts. Histologic analysis of fibrosis in rodent allografts at an early timepoint exhibited increases in total tissue accumulation (1.48 – 5.15 fold) and significant increases in various focal regions (left ventricle, ***p &lt; 0.001; interventricular septum, ****p &lt; 0.0001) compared to the native hearts. Furthermore, large amounts of cellular infiltrate and marginal increases in cardiac diameter (1.10 – 1.42 fold) were observed in the transplants. While the scarcity of immunofluorescence signal for lymphatic markers has caused cardiac lymphatic quantification to be inconclusive, evaluation of lymphatic transport revealed fluctuating time-dependent circulating FITC levels (0.002 - 0.010 mg/mL; *p &lt; 0.05) suggesting multi-teared compartmental release properties between the microcirculatory system, lymphatic system, and cardiac tissue. Conclusion: The HAHT rodent model provides a promising modality to assess both lymphatic transport and transplant rejection. Moreover, these studies will progress understanding of transplant rejection’s pathological intricacies and provide the groundwork for lymphangiogenic-based therapeutic intervention.
Abstract P3073: Altered Mitochondrial Mg <sup>2+</sup> Homeostasis In Liver Links Lipid Metabolism, Inflammation And Atherogenesis
Authors: THIRUVELSELVAN PONNUSAMY, Prema Velusamy, Shanmughapriya Santhanam
Journal: Circulation Research (2022)

Although evidences show the role of Mg 2+ in lipid metabolism and atherosclerosis, the molecular mechanism by which loss of Mg 2+ homeostasis promotes cardiovascular disease (CVD) is not known. Mg 2+ homeostasis is regulated by mitochondria and Mrs2 is the only known molecular machinery associated with mitochondrial Mg 2+ influx. To begin elucidating the importance of Mg 2+ homeostasis in lipid metabolism and CVD we made liver-specific Mrs2 KO mouse (Mrs2 Δhep ). Liver being the central hub of lipid metabolism, we asked whether loss of Mrs2 alters lipid metabolism and lipoprotein profile. Our results show increased accumulation of hepatic triacylglycerol (TG) and cholesterol in Mrs2 Δhep . Consistent with increased TG/cholesterol, plasma cholesterol and oxidized low density lipoprotein (ox-LDL) levels significantly differed between control and KO. Because ox-LDL contribute to atherosclerosis, we hypothesized altered hepatic lipid metabolism to induce inflammation, immune imbalance and accelerate lesions through modified atherogenic lipoprotein and cytokine profile. Quantification of plasma cytokines and chemokines were performed using the proteome profiler. Because T cells are critical drivers and modifiers of atherosclerosis, we quantified the lymphocyte and monocyte subsets by flow cytometry. Because T regulatory cells have anti-antherogenic roles, we studied the effect of ox-LDL on Tregs. Our results show increased and decreased levels of inflammatory and anti-inflammatory cytokines respectively in Mrs2 Δhep . In Mrs2 Δhep stimulation with ox-LDL showed an increased antigen specific proliferation of T-cells. We also observed increased and decreased population of Th17 and Tregs respectively. The decrease in Tregs population was attributed to increased apoptosis. In conclusion our observation suggests that high levels of ox-LDL in Mrs2 Δhep to induce inflammation and inflammatory cell expansion accompanied by apoptosis in Tregs. Our results conclude dysregulated Mg 2+ homeostasis to alter lipid metabolism and atherogenesis by inducing inflammation and compromised Tregs population. Our study will be the first of its kind to establish a triangular molecular link between Mg 2+ homeostasis, lipid metabolism, and atherogenesis.
Abstract P2036: Investigating Variants Of <i>Hdac7</i> In Mammalian Heart Regeneration
Authors: Tyler Buddell, Alexandra Purdy, Xiangwen Peng, Mary Kolell, Samantha Swift, Samantha Paddock, Caitlin Omeara, Michaela Patterson
Journal: Circulation Research (2022)

The longstanding belief in the field is the mammalian heart is incapable of regenerating. However, findings regarding the variability of regenerative capacity of mammalian hearts are opening the door for such a possibility. Mononuclear diploid cardiomyocytes (MNDCMs) are a subpopulation of CMs believed to be capable of mounting a regenerative response and the prevalence of the MNDCM population in mammalian hearts is a variable trait. Thus, if we can understand the genetic mechanisms governing the MNDCM variability, it could indicate strategies to stimulate an endogenous regenerative response. Using a genome-wide association approach across a panel of genetically diverse inbred mice, Dr. Patterson identified genes associated with the frequency of MNDCMs in the uninjured adult heart. From this genetic screen, she validated the gene Tnni3k as one regulator of CM ploidy and regenerative competence after injury. Here, we follow a second novel locus identified from this screen found on chromosome 15, which includes the gene Hdac7. Previously published RNA-seq data on isolated CMs indicate that Hdac7 expression levels increase during the first postnatal week, a time that coincides with the onset of cellular senescence, CM polyploidization, and the loss of innate regenerative capacity in the heart. Using a CM specific Hdac7 conditional knockout mouse, we found that loss of Hdac7 in CMs from birth increases CM DNA synthesis, increases CM ploidy, and increases average CM cell length. Moreover, we identified a protein coding variant of Hdac7 that corresponds to differences in frequency of MNDCM between members of the mouse diversity panel. Finally, we have gathered preliminary findings that suggest genetic epistasis between Hdac7 and Tnni3k. Specifically, Hdac7;Tnni3k double knockout animals display more MNDCMs than Tnni3k knockout did on its own. Our findings suggest Hdac7 negatively regulates DNA synthesis; a key part of the cell cycle that has the potential as a therapeutic target for the stimulation of a proliferation response. In addition, these findings showcase complex genetic interactions regulating CM regeneration, suggesting that combinatorial approaches can enhance regenerative responses.
Abstract P1049: Determination Of Proteome-wide Post-translational Modifications By Lysine Acetylation In Ischemic Cardiac Cells
Authors: Aishwarya Rajakumar, Isabela Beatriz de Lima, Manish K Gupta
Journal: Circulation Research (2022)

Introduction: In ischemic cardiomyopathy, cardiac muscle gets damaged due to ischemia and the heart loses its ability to pump blood properly, leading to heart failure. Considering the effect of ischemic cardiomyopathy on the global population, it is vital to understand the impact of ischemia on the cardiac cells and how ischemic condition changes different cellular functions through post-translational modifications (PTM) of cellular proteins. Acetylation, one such PTM, is known to affect protein synthesis, epigenetic modification, and metabolism. This study aims to identify global acetylation changes due to ischemic conditions. Methods: Rat ventricular cardiomyocytes were exposed to reduced oxygen conditions for 12 hours, and the proteins were isolated for acetylation analysis. Mass spectrometry was performed on these proteins to analyze global changes in acetylation due to ischemia. Results: Our result shows that 180 proteins are differentially acetylated during ischemia, and these acetylated proteins are found to be localized in different subcellular organelles like mitochondria, nucleus, cytoplasm, etc. These PTMs tune the cellular protein function and regulate different cellular functions such as protein synthesis, epigenetic modification, and metabolism. Conclusion: Understanding cellular changes due to post-translational acetylation modification may help in the design of therapeutic agents against ischemia-mediated heart disease.
Abstract P3129: Functional Coupling Of TRPM2 And Extrasynaptic NMDARs Exacerbates Excitotoxicity In Ischemic Stroke
Authors: Pengyu Zong, jianlin feng, Zhichao Yue, Yunfeng Li, Gongxiong Wu, Baonan Sun, Yanlin He, Barbara Miller, Albert S Yu, Zhongping Su, Jia Xie, Yasuo Mori, Bing Hao, Lixia Yue
Journal: Circulation Research (2022)

Introduction: Ischemic stroke caused a heavy burden on public health. NMDA receptor (NMDAR) mediated excitotoxicity was thought to be the culprit for neuronal death during ischemic stroke. However, NMDAR antagonists all failed to show protective effects in human patients. The heat-sensitive ion channel TRPM2 is Ca 2+ -permeable and usually activated under oxidative stress conditions. TRPM2 is abundantly expressed in the brain and promotes neuronal death during ischemic stroke, whereas the underlying mechanisms remain elusive. Hypothesis: Oxidative stress is a hallmark of brain damage during ischemic stroke. We hypothesized that TRPM2 is important in magnifying NMDAR-mediated excitotoxicity. Methods: Neuron specific TRPM2 knockout was achieved by crossing nestin-cre mice with Trpm2 fl/fl mice. Middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation (OGD) were performed to mimic ischemic stroke in vivo and in vitro, respectively. Co-immunoprecipitation and direct binding assay were used to examine protein-protein interaction. Subcloning and mutagenesis were used to identify interaction details. Interfering peptide specifically disrupting TRPM2-NMDAR interaction was designed and synthesized. Cortical neurons were isolated and cultured, Fura-2-AM and Rhodamine-123 imaging were used to examine Ca 2+ overload and mitochondrial dysfunction, respectively. Synaptic and extrasynaptic NMDAR mediated responses were separated, and synaptosome was isolated to examine the influence of TRPM2 on NMDAR and expression of TRPM2 in neurons at different sites, respectively. Results: Neuron specific TRPM2 knockout alleviates ischemic stroke in mice. TRPM2 physically and functionally interacts with extrasynaptic NMDAR, which enhances excitotoxity. The EE 3 motif in TRPM2 directly associates with the KKR motif in NMDAR. Uncoupling of TRPM2-NMDAR association using a disrupting peptide TAT-EE 3 prevents OGD-induced Ca 2+ overload and mitochondrial dysfunction in neurons, and protects mice against MCAO-induced brain injury. Conclusion: Therapeutic interfering peptide TAT-EE 3 attenuates ischemic stroke. Targeting the TRPM2-NMDAR coupling could be a promising strategy for screening more effective therapies for ischemic stroke.
Computed Tomography of the Lungs as a Means of Predicting Lethal Outcome in Cancer Patients with Pneumonia Caused by the SARS-CoV-2 Virus
Authors: V. V. Parshin, D. A. Lezhnev, E. E. Berezhnaia, A. V. Mishina
Journal: Radiology - Practice (2022)

The global scientific community has recognized the high importance of lung CT as a diagnostic method. The objective of this study is to prove the significance of lung CT as a means of predicting fatal outcomes of COVID–19 viral pneumonia in patients with a severe and extremely severe course of the disease. The volume of lung damage was retrospectively estimated in postmortem studies of 26 patients with the burden of cancer and in 78 patients without any cancer history (the control group). Lung CT was performed on the day of death and maximum 3 days before it. We concluded that the patients with cancer died with a lesion volume two times smaller than those without cancer, 32.38 ± 17.41% and 69.21 ± 11.63%, respectively. Thus, lung CT is not only a diagnostic tool, but it can also predict the fatal outcome of SARS-CoV-2 pneumonia (COVID-19) in patients with a severe and extremely severe course of the disease.
Abstract P1109: Investigating The Role Of Human Conserved Microrna-193 In The Aging <i>Drosophila</i> Heart
Authors: Alyssa M Hohman, Elizabeth M McNeill
Journal: Circulation Research (2022)

MicroRNAs (miRNAs) are short, non-coding, RNAs that post-transcriptionally regulate gene expression and are ideal candidates for the regulation of the genes responsible in the heart. Profiling studies have shown circulating miRNAs to be implicated in human cardiovascular disease with the potential to be used as biomarkers for various cardiovascular pathologies. Highly conserved with Drosophila miR-193, human miR-193 is expressed in the heart and has been established as a biomarker to distinguish between patients with different types of heart failure, including HFPEF, hypertrophic cardiomyopathy, ischemia reperfusion injury, right ventricular remodeling, cardiac fibrosis, and congenital heart disease. However, without the mechanism and regulation of its target genes, the use of miR-193 as a biomarker or therapeutic is limited. We have characterized the impact of miR-193 loss on homoeostasis of heart morphology and function in drosophila during aging using a combination of null mutants and heart specific dysregulation of miR-193 expression. Using SOHA (semi-automated optical heartbeat analysis), we observed changes occurring to heart structure and function with a loss of miR-193. With miR-193 dysregulation, significant changes in heart rate, heart size (diastolic and systolic diameters), arrhythmia index, and diastolic/relaxation interval time, began at 10 days post-eclosion and continued as the flies aged. Understanding the role of miRNAs in specific tissues and disease states will ultimately depend on our ability to dissect the fundamental strategies and mechanisms by which miRNAs regulate cardiac biology. Using in silico analysis, we have identified multiple human conserved putative miRNA-target gene interactions to further characterize the molecular mechanisms underlying the observed phenotypes. Our results suggest that the human conserved Drosophila miR-193 is essential for normal cardiac function. In miR-193 loss of function, we see significant changes to heart rate, heart size, and interval time consistent with an early aging phenotype. The conservation of miR-193 and its predicted gene targets enable us to discover the molecular mechanisms that underlie miRNA dysregulation in cardiovascular disease.
Abstract P1067: IRS Mediated Recruitment Of PI3Kgamma By Insulin Inhibits Beta-adrenergic Receptor Function
Authors: Anita Sahu, Sromona D Mukherjee, Conner Witherow, Kate Stenson, John Tesmer, Maradumane L Mohan, Sathyamangla V Naga Prasad
Journal: Circulation Research (2022)

Insulin (INS) treatment results in impaired response to β-agonist isoproterenol (ISO) associated with phosphorylated β2-adrenergic receptor (β2AR) and impaired cAMP response. Although INS does not mediate dissociation of G-protein Gβγ subunits, yet surprisingly recruits phosphoinositide 3-kinase γ (PI3Kγ) to the plasma membrane. Correspondingly, knock-down of PI3Kγ (PI3Kγ KD) in HEK 293 or ablation in primary adult cardiomyocytes and fibroblasts (isolated from PI3Kγ knockout mice) abrogated β2AR phosphorylation reflecting a key role for PI3Kγ in retaining β2AR phosphorylation. Also, adult cardiomyocytes isolated from C57Bl6 mice showed significant loss of in vitro ISO-stimulated cardiomyocyte contraction upon INS pre-treatment which was remarkably preserved in the PI3Kγ knockout cardiomyocytes despite INS. As PI3Kγ is traditionally recruited to the βAR complex by the Gβγ subunits, we hypothesized that INS-mediates Gβγ-independent recruitment of PI3Kγ to the βAR complex underlying its dysfunction. INS stimulation is known to recruit insulin receptor substrate (IRS 1 &amp; 2) to the receptor complex, and therefore, we tested whether PI3Kγ interacts with IRS 1/2 leading to Gβγ-independent recruitment of PI3Kγ to the β2AR complex. Immunoprecipitation PI3Kγ following INS showed that PI3Kγ interacts with IRS2 recruiting PI3Kγ to the β2AR complex bypassing the traditional Gβγ-dependent pathway. Since PI3Kγ KD resulted in loss of INS-mediated β2AR phosphorylation, we tested whether PI3Kγ inhibits protein phosphatase 2A (PP2A) function impairing β2AR de-phosphorylation. INS treatment resulted in significant loss of β2AR-associated PP2A activity which was rescued in PI3Kγ KD cells showing that PI3Kγ impairs PP2A function. Furthermore, our studies show that PI3Kγ phosphorylates the endogenous inhibitor of PP2A, I2PP2A which then robustly binds and inhibits PP2A activity impairing β2AR dephosphorylation. Consistently, CRISPR ablation of I2PP2A relieves this inhibition on PP2A leading to increased PP2A activity. This reduces accumulation of phosphorylated βARs despite the presence of PI3Kγ showing an underappreciated regulation of PP2A by insulin through non-canonical recruitment of PI3Kγ that impairs β2AR function.
Abstract P2013: Transcription Fidelity Dysregulation In Heart Failure Pathogenesis
Authors: Weijia Luo, Zhishi Chen, Wei Yu, Keith Youker, Jiang Chang
Journal: Circulation Research (2022)

Using deep sequencing combined with computational biology, we found that the failing human hearts (n=3) contain a significant amount of aberrant transcripts arising from widespread spurious intragenic transcription initiations. The same phenomenon was detected in failing mouse hearts (n=3) induced by pressure overload and ischemia injury. Therefore, we hypothesize that spurious transcripts accumulation is a causative factor promoting heart failure (HF). The SET domain containing 2 (Setd2), an H3K36 tri-methylase, is a key regulator for transcription fidelity. The Setd2 modified H3K36me3 prevents RNA polymerase II (Pol II) entry from the gene body and the subsequent cryptic transcription initiation. In the same cohort of failing human and mouse hearts, we found that the SETD2 and H3K36me3 levels were concurrently reduced. To further test our hypothesis, we generated cardiac-specific Setd2-Knockout mice. The mice (n≥8) developed a typical HF progression phenotype: initial compensatory hypertrophy followed by a gradually deteriorating HF with chamber dilation. Transcriptome analysis revealed an accumulation of spurious transcripts in pre-hypertrophic Setd2 -/- cardiomyocytes (n=3). New intragenic transcription initiation sites were identified by DECAP-seq in the knockout (n=3), confirming that the increased aberrant transcripts resulted from spurious Pol II entry. Using ribosome footprinting assay (n=3) to map the translation initiation sites, we found that the aberrant transcripts were partially translated into micro peptides in the Setd2 -/- heart, suggesting that the accumulated aberrant transcripts and micro peptides together promote cardiac hypertrophy. Finally, we developed transgenic mice overexpressing human SETD2 (Tg-MHC-SETD2) in the heart. SETD2 overexpression repressed TAC-induced accumulation of spurious transcripts in cardiomyocytes (n=3). The transgenic mice (n≥6) were resistant to pressure overload stress with less cardiac hypertrophy and improved cardiac contractility. Together, we report that dysregulated transcription fidelity causes adverse aberrant transcripts accumulation leading to cardiac hypertrophy and heart failure. This new mechanism provides potential new therapeutic targets for HF.
Abstract P2111: Hutchinson Gilford Progeria Patient-specific Induced Cardiomyocyte Model Carrying Lamin A Gene Variant C.1824 C &gt; T
Authors: Selene G Perales, Sheeja Rajasingh, Vinoth Sigamani, Narasimman Gurusamy, Johnson Rajasingh
Journal: Circulation Research (2022)

Background: Hutchinson-Gilford progeria (HGP) is a rare genetic disorder in which children age rapidly. They suffer from atherosclerosis, cardiovascular diseases, and strokes. The LMNA variant c.1824C&gt;T accounts for ~90% of HGP cases. This variant causes an abnormal Lamin A protein called progerin. The detailed molecular mechanisms of Lamin A in the heart remain elusive due to the lack of appropriate in vitro models. Hypothesis: We hypothesize that HGP patient’s induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMCs) will provide a model platform to study the cardio-pathologic mechanisms associated with progeria. Methods and Results: We performed in silico analysis of LMNA variant c.1824C&gt;T to determine its effects on Lamin A structure and stability. For validation , skin fibroblasts (SFs) from a de-identified HGP patient (hPGP1, proband) and parents were obtained from the Progeria Foundation. Through Sanger sequencing (Fig 1A) and restriction fragment length polymorphism, with enzyme EciI , targeting Lamin A, we characterized hPGP1-SFs as heterozygous mutants for variant c.1824 C&gt;T. Then, we reprogrammed the three SFs into iPSCs (Fig 1B) using a safe mRNA-based reprogramming method , and differentiated them into iCMCs, which gained beating on day 7. We found that hPGP1-iCMCs (Fig 1C) had an irregular contractile function by Particle Image Velocimetry Analysis and decreased cardiac-specific gene and protein expressions by qRT-PCR and Western Blot. Conclusions: We successfully generated iCMCs from a progeria patient carrying LMNA variant c.1824C&gt;T. These iCMCs were found to be functionally and structurally defective when compared to normal iCMCs. Our in vitro model will help elucidate the role of Lamin A and the cardio-pathologic mechanisms associated with progeria.